With solar and wind at grid parity in many places, it’s established that clean energy can be produced economically. But if you produce more than you need, where do you put it? And where do you get energy on a windless night?

China’s struggle with overproduction has shown what you don’t want to do when energy is abundant: curtail production. And the current approach to high demand–firing up expensive peakers that otherwise sit idle–is wasteful and inefficient.

With carbon energy, storage and consumption are the same thing: you burn it when you need it. With clean energy, storage comes after production, and requires new approaches. Those can include gravity and salt, but increasingly, it means batteries, and at this moment, that means Tesla.

The company began mass production at their Gigafactory this year, and quietly put their Mira Loma utility-scale battery storage facility into production in January, far sooner than originally scheduled. On the consumer front, they’re expected to start delivering the second version of their Powerwall home storage battery this month.

Battery storage it at an inflection point, just now becoming technically and economically viable at scale, and catalyzing further growth in solar at both the consumer and utility level. The third leg of the stool is grid technology, which we’ll report on in an upcoming newsletter.